Irritable bowel syndrome (IBS) is a very common chronic condition characterized by abdominal pain and abnormal stools. Unlike Crohn's disease and ulcerative colitis, there is no inflammation of the digestive tract. The exact cause of IBS is unknown, but some people develop it after an infection of the digestive tract. Symptoms can include abdominal pain, bloating, diarrhea, and constipation. IBS can frequently be diagnosed on the basis of symptoms, although some patients may undergo lab testing or colonoscopy to rule out other disorders. Treatment of IBS is focused on controlling symptoms with dietary changes, and a variety of over the counter and prescription medications.